Conflict Checker generates incorrect results. For example, the conflict conflict checker brings up all the change requests that has the same CI regardless the planned change window.

There could be many reasons, but the most possible cause is that the related conflict check scripts are customised.

1. Open "ChangeCheckConflicts" script include: https://[instance_url]/sys_script_include.do?sys_id=4e2ce1c5c1252a7b1faa471f1683fd7b
2. Check if this script include is customised.
3. If yes, revert this to Out-of-box state. See details of how to revert an object version here.